Grade 9 Electricity Practice Exam

In parallel, there are multiple paths for current between the same two points. Because the voltage across every branch is the same as the source, each resistor draws a current I = V/R_i. Adding another resistor adds another path, so the total current from the source increases. With the same supply voltage, increasing the total current means the equivalent resistance must drop: R_total = V / I_total. For equal resistors, this becomes R/n, so more branches mean a smaller total resistance.

That’s why the total resistance decreases when you add resistors in parallel. The current in each branch doesn’t necessarily rise just from adding a branch, since it’s set by V and the branch’s own resistance, and the voltage across each branch stays the same. Adding branches also doesn’t increase the voltage across each resistor, it remains equal to the source. And the total resistance certainly does not increase.